Re: [Jscheme-user] Handling Java Array Parameters

[Timothy J. H. <tim...@ma...>]

On Monday, March 1, 2004, at 09:59 PM, Enrique Ricoy Belloc wrote:

> I've started using Jscheme, I want to implement the
> following code, but
> don't know quite how to handle the URL[] definition:
>
>
> URL[] urls = new URL[] {
> new File("C:\\Program Files\\Microsoft SQL Server 2000
> Driver for
> JDBC\\lib\\msbase.jar").toURL(),
> new File("C:\\Program Files\\Microsoft SQL Server 2000
> Driver for
> JDBC\\lib\\mssqlserver.jar").toURL(),
> new File("C:\\Program Files\\Microsoft SQL Server 2000
> Driver for
> JDBC\\lib\\msutil.jar").toURL()
> };

I tend to use the (list->array TYPE LIST) procedure
which converts a list into an array of the specified type.
So, to convert a list L of filenames into an array of URLs
you could use the following procedure:

 > (define (filenames->urlarray L)
   (list->array java.net.URL.class
     (map .toURL
        (map java.io.File. L))))
......

which could be applied as follows:

 > (define z (filenames->urlarray (list "lib/jscheme.jar" 
"lib/applet.jar")))
.....
 > z
#(file:/Users/tim/Research/Software/jscheme/lib/jscheme.jar 
file:/Users/tim/Research/Software/jscheme/lib/applet.jar)

Hope this helps,
---Tim---

P.S. You can access array elements with (Array.get z n) and (Array.set 
z n v), e.g.

 > (Array.get z 0)
...
 > (Array.set z 1 (Array.get z 0))
...



> URLClassLoader loader = new URLClassLoader(urls);
> Driver d = (Driver) Class.forName(driverStr, true,
> loader).newInstance();

This would rewrite to
(define loader (URLClassLoader. urls))
(define d (.newInstance (Class.forName driverStr #t loader)))

>
> --end--
>
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